The present invention concerns supported Ti.sup.III catalysts.
In the polymerization of one or more .alpha.-olefins, either TI.sup.III or Ti.sup.IV compounds can be employed. It is highly desirable to employ the catalysts on an inert inorganic support. It is also desirable to employ Ti.sup.III compounds when relatively lower melt index polymers are desired. However, supported Ti.sup.III catalysts are inconvenient to prepare since they are generally insoluble. Therefore, in order to prepare supported Ti.sup.III compounds, the solid support and the solid Ti.sup.III compound are roll milled so as to prepare the supported Ti.sup.III catalyst. The present invention provides a method for preparing supported Ti.sup.III catalysts with ease by merely contacting a mixture of the support and a Ti.sup.IV compound containing at least two halogen atoms in a hydrocarbon medium with a hydroquinone compound thereby forming the Ti.sup.III compound in situ.